Coriolis flowmeters

Coriolis flowmeters cover a wide range of process applications - from standard applications to highly demanding applications in many industries.

Typcial areas of application are:

• Chemical industry: Measurement of chemicals such as acids, alkalis, bleaching agents, dyes, chlorine and sulphur compounds

• Oil & gas: dosing, loading and unloading of hydrocarbons, measurement of cryogenic media such as LNG

• Marine: Bunkering, consumption and emission measurement of marine fuels such as diesel, marine gas oil and others

• Food & pharma: Hygienic applications for milk, chocolate, jam, ice cream; solvent extracts, ultrapure water, etc.

• Media containing solids and media with high viscosity: bitumen, fats, oils, sludge, dough, honey, syrup, molasses, pulp, spinach, minced meat, plant-based foods, pet food

• Gases: hydrogen, CO₂, supercritical gases

• Concentration measurements: alcohol in spirits production, fructose, sewage sludge, etc.

• Extreme conditions: high and low temperature ranges (-200...+400°C), liquids with gas entrainment of up to 100%

• Safety & custody transfer applications: Safety Instrumented Systems (SIS), custody transfer (according to MID, OIML, AGA, etc.)

• High-accuracy dosing applications, measuring very small quantities or loading large quantities of several thousand tonnes per hour

• Other: Batching / filling systems, dispensing systems (e.g. for LPG)

KROHNE was the first manufacturer to develop and launch a Coriolis flowmeter with a single straight measuring tube. It is very well suited for shear-sensitive, inhomogeneous liquids and aggressive chemicals. The single straight tube meter shows its particular strengths in applications with highly viscous liquids containing large amounts of fibres and solids, such as pulp, crude oil or sludge. Users benefit from significantly lower wear and maintenance requirements compared to Coriolis meters with a twin bent tube design.

As the measuring tube can also be drained and is easy to clean, it is also the preferred choice for increased hygienic requirements. Another advantage of the straight tube meter is the significantly lower pressure loss compared to standard mass flowmeters with flow splitters. Today, KROHNE is still the only manufacturer to offer the single straight tube meter in four different materials: stainless steel, Alloy 22 (also known as Hastelloy® C22 ), titanium and tantalum.

The pressure loss of Coriolis meters depends on the pipe design. Coriolis devices with a single straight tube design, such as the OPTIMASS 7400 from KROHNE, can be regarded as part of the pipework and therefore have virtually no influence on the overall pressure loss in the system. They operate with virtually no pressure loss. Bent tube flowmeters generate a higher pressure loss than straight tube designs for the same size or capacity.

The laws of physics dictate that the higher the number of bends and the tighter the bend angles, the greater the pressure drop created. In addition, where bent tube designs require elevated pipework there will, by definition, be an increase in pipeline length and the number of angled fittings required to achieve the installation. This in turn provides an additional contribution to the overall pressure drop calculation required for bent tube meters. The greater the total pressure loss of the installed flowmeter, the higher the costs for investing in more powerful pumps and for energy consumption.

In order to keep the pressure loss in mass flowmeters with a bent tube or a flow divider as low as possible, KROHNE's OPTIMASS flowmeter series feature optimised flow splitter technology, which ensures that the pressure loss is as low as possible.

The difficulty in measuring a liquid with entrained gas increases with the fraction of gas. Without entrained gas, the measuring tubes in a Coriolis mass flowmeter have the desired regular oscillation. Gas entrained in the liquid dampens the regular oscillation of the measuring tubes, and as the gas content increases, the oscillation can come to a complete stop, causing the Coriolis flow measurement to fail completely.

To solve this problem, KROHNE was the first manufacturer of Coriolis mass flowmeters to develop and commercialise EGM TM (Entrained Gas Management) to solve these challenges. Today, all products in the OPTIMASS flowmeter series using the MFC 400 signal converter are equipped with EGM TM . EGM TM utilises powerful control algorithms that allow a Coriolis flowmeter to maintain operation over a wide range of gas fractions and complex flow conditions - even during a complete transition from a pure liquid phase to a gas phase and back. As a result, mass flow and density measurements remain stable, which the OPTIMASS devices have successfully demonstrated in many applications such as filling, loading, dosing or empty-full-empty applications

State-of -the-art mass flowmeters offer extensive possibilities for self-monitoring, application diagnostics and on-site verification. For example, OPTIMASS Coriolis meters from KROHNE with OPTICHECK technology built-in have integrated diagnostic functions that continuously monitor all measurable parameters, electronic components such as CPUs, memory and internal bus connections as well as the flow sensor during operation. The meters comply with the NAMUR NE 107 industry standard for status processing.

In addition, the diagnostic software provides an insight into process and auxiliary values in order to ultimately confirm the condition of the process medium. OPTIMASS meters can even generate warning messages in the event of gas inclusions and when a certain proportion of gas bubbles or solids is exceeded, thus providing valuable information about the process. The Coriolis flowmeters from KROHNE can also be checked via on-site verification in the field- including report generation - also wirelessly via Bluetooth® or via DTM. Redundant storage of all device configuration data allows the flow converter to be replaced at any time without the need for manual reconfiguration.

Mass flowmeters are considered to be particularly long-term stable flowmeters. Nevertheless, it is advisable to carry out a zero point adjustment at regular intervals. The flow in the Coriolis device must be brought to a standstill. Valves installed in front of and behind the meter are ideal for this. In the filled state, i.e. without movement in the measuring device, the zero flow rate is determined. This increases the measuring accuracy and improves the performance at low flow rates.

Recalibration of flowmeters is often mandated by the regulations and standards of the respective industries. Typical intervals here are between one and two years. However, there is no generally applicable test interval. This depends on the application and the load on the mass flowmeter. Particles in the medium can lead to increased wear of the measuring tube and thus to changes in the measuring accuracy. Deposits such as oxide or salt layers can also affect the balance of the measuring tubes. In these cases, recalibration in a certified calibration laboratory is recommended.

Our meters can be calibrated and certified according to various standards such as OIML or the European Measuring Instruments Directive (MI-002 and 005), and comply with API and AGA. The standards we use for calibration are ISO/IEC 17025 accredited and traceable to international or national standards. Regular inspections by national metrology institutes, round robin tests and alignments with national and international metrological standards guarantee the quality and comparability of our calibration rigs. Click here for an overview of KROHNE's calibration services.